Inspection and evaluation of cement-based materials such as concrete is of great interest to the construction industry. In particular, real-time and on-site evaluation of water-to-cement ratio (w/c) is an important practical issue, since the compressive strength of a concrete structure is significantly influenced by its w/c. Currently, there is no single real-time, on-site, relatively inexpensive, easy-to-implement, and operator friendly technique for evaluating this parameter. Microwave nondestructive testing and evaluation techniques have shown great promise when used for inspection and evaluation of the properties of cement-based materials. In this paper, the optimal design of a monopole antenna probe used to evaluate w/c of fresh cement-based materials in real-time and in-situ is presented. This probe, operating at 3 GHz, is used along with a reflectometer whose DC output voltage is shown to be linearly correlated to w/c of fresh cement paste and fresh concrete specimens. This paper presents the optimal probe design procedure, the experimental verification of the results, and the results of using the custom-made reflectometer for quick and robust w/c measurement of fresh cement paste and concrete


Electrical and Computer Engineering

Keywords and Phrases

3 GHz; DC Output Voltage; Cement Paste; Cements (Building Materials); Compressive Strength; Concrete; Construction Industry; Dielectric Measurement; Fresh Portland Cement-Based Materials; Microwave Reflectometry; Monopole Antenna Probe; Monopole Antennas; Nondestructive Testing; On-Site Microwave Technique; Optimal Probe Design Procedure; Probes; Real-Time Technique; Reflectometer; Robust On-Site Technique; Water; Water-To-Cement Ratio; Electromagnetic Formulation-Probe Development and Antennas; Infrastructure Testing and Cement-Based Material Evaluation; Material Characterization

International Standard Serial Number (ISSN)


Document Type

Article - Journal

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Final Version

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© 2001 Institute of Electrical and Electronics Engineers (IEEE), All rights reserved.